logger • man page

logger • man page

logger (1)

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(The comments found at the beginning of the groff file "man1/logger.1".)

NAME

logger - enter messages into the system log

SYNOPSIS

logger
[options]
[message]

DESCRIPTION

logger
makes entries in the system log.

When the optional message argument is present, it is written
to the log. If it is not present, and the -f option is not
given either, then standard input is logged.

OPTIONS

-d, --udp

Use datagrams (UDP) only. By default the connection is tried to the
syslog port defined in /etc/services, which is often 514 .

-e, --skip-empty

When processing files, empty lines will be ignored. An empty line
is defined to be a line without any characters. Thus a line consisting
only of whitespace is NOT considered empty.
Note that when the --prio-prefix option is specified, the priority
is not part of the line. Thus an empty line in this mode is a line that does
not have any characters after the priority (e.g. "<13>").

-f, --file file

Log the contents of the specified file.
This option cannot be combined with a command-line message.

-i

Log the PID of the logger process with each line.

--id[=id]

Log the PID of the logger process with each line. When the optional
argument id is specified, then it is used instead of the logger
command's PID. The use of --id=$$
(PPID) is recommended in scripts that send several messages.

--journald[=file]

Write a systemd journal entry. The entry is read from the given file,
when specified, otherwise from standard input.
Each line must begin with a field that is accepted by journald; see
systemd.journal-fields(7)
for details. The use of a MESSAGE_ID field is generally a good idea, as it
makes finding entries easy. Examples:

Notice that
--journald
will ignore values of other options, such as priority. If priority is
needed it must be within input, and use PRIORITY field. The simple
execution of
journalctl
will display MESSAGE field. Use
journalctl --output json-pretty
to see rest of the fields.

--msgidMSGID

Sets the RFC5424 MSGID field. Note that the space character is not permitted
inside of MSGID. This option is only used if --rfc5424 is
specified as well. Otherwise, it is silently ignored.

--no-act

Causes everything to be done except for the write the log message to the system
log, remove connection or journal. This options is usable together with
--stderr for testing purpose.

--sizesize

Sets the maximum permitted message size to size. The default
is 1KiB characters, which is the limit traditionally used and specified
in RFC 3164. With RFC 5424, this limit has become flexible. A good assumption
is that RFC 5424 receivers can at least process 4KiB messages.
Most receivers accept larger than 1KiB message over any type of syslog
protocol. As such, the --size option affects logger in
all cases (not only when --rfc5424 was used).
Note: the message size limit limits the overall message size, including
the syslog header. Header sizes vary depending on options selected and hostname
length. As a rule of thumb, headers are usually not longer than 50 to 80
characters. When selecting maximum message size, it is important to ensure
that the receiver supports the max size as well, otherwise messages may
become truncated. Again, as a rule of thumb two to four KiB message size
should generally be OK, whereas anything larger should be verified to work.

-n, --server server

Write to the specified remote syslog server
instead of to the system log socket. Unless
--udp or --tcp
is specified, logger will first try to use UDP,
but if thist fails a TCP connection is attempted.

-P, --port port

Use the specified port. When this option is not specified, the
port defaults to syslog for udp and to syslog-conn for tcp connections.

-p, --priority priority

Enter the message into the log with the specified priority.
The priority may be specified numerically or as a
facility.level
pair.
For example, -p local3.info
logs the message as informational in the local3 facility.
The default is user.notice.

--prio-prefix

Look for a syslog prefix on every line read from standard input.
This prefix is a decimal number within angle brackets that encodes both
the facility and the level. The number is constructed by multiplying the
facility by 8 and then adding the level. For example, local0.info,
meaning facility=16 and level=6, becomes <134>.

If the prefix contains no facility, the facility defaults to what is
specified by the -p option. Similarly, if no prefix is provided,
the line is logged using the priority given with -p.

This option doesn't affect a command-line message.

--rfc3164

Use the RFC 3164 BSD syslog protocol to submit messages to a remote server.

--rfc5424[=without]

Use the RFC 5424 syslog protocol to submit messages to a remote server.
The optional without argument can be a comma-separated list of
the following values: notq, notime, nohost.
The notq value suppresses the time-quality structured data
from the submitted message. (The time-quality information shows whether
the local clock was synchronized plus the maximum number of microseconds
the timestamp might be off.) The notime value (which implies
notq) suppresses the complete sender timestamp that is in
ISO-8601 format, including microseconds and timezone.
The nohost value suppresses
gethostname(2)
information from the message header.

The RFC 5424 protocol has been the default for
logger
since version 2.26.

--octet-count

Use the RFC 6587 octet counting framing method for sending messages. When
this option is not used, the default is no framing on UDP, and RFC6587
non-transparent-framing (also known as octet stuffing) on TCP.

-s, --stderr

Output the message to standard error as well as to the system log.

-T, --tcp

Use stream (TCP) only. By default the connection is tried to the
syslog-conn
port defined in /etc/services, which is often
601.

-t, --tag tag

Mark every line to be logged with the specified
tag.

-u, --socket socket

Write to the specified
socket
instead of to the system log socket.

--socket-errors[=mode]

Print errors about Unix socket connections. The mode can be a value of
off, on, or auto. When the mode is auto logger will detect
if the init process is systemd, and if so assumption is made /dev/log can be
used early at boot. Other init systems lack of /dev/log will not cause errors
that is identical with messaging using
openlog(3)
system call. The
logger(1)
before version 2.26 used openlog, and hence was inable to detected loss of
messages sent to Unix sockets.

The default mode is auto. When errors are not enabled lost messages are
not communicated and will result to successful return value of
logger(1)
invocation.

--

End the argument list. This allows the message
to start with a hyphen (-).

-V, --version

Display version information and exit.

-h, --help

Display help text and exit.

RETURN VALUE

The
logger
utility exits 0 on success, and >0 if an error occurs.

FACILITIES AND LEVELS

Valid facility names are:

auth

authpriv

for security information of a sensitive nature

cron

daemon

ftp

kern

cannot be generated from userspace process, automatically converted to user

lpr

mail

news

syslog

user

uucp

local0

to

local7

security

deprecated synonym for auth

Valid level names are:

emerg

alert

crit

err

warning

notice

info

debug

panic

deprecated synonym for emerg

error

deprecated synonym for err

warn

deprecated synonym for warning

For the priority order and intended purposes of these facilities and levels, see
syslog(3).